Bermuda grass (Cynodon dactylon) is an important source of pollen allergens in many areas of the world, especially in tropical and sub-tropical climates. These allergens have been studied by a number of means including IgE immunoblotting (Ford D., and Baldo, B. A. J. Allergy Clin. Immunol. 79: 711-720 (1987); Shen H. D., et al., Clin. Allergy 18: 401-409 (1988), column chromatography (Orren, A., and Dowdle, S. Afr. Med. J. 51: 586 (1977); Matthiesen et al., J. Allergy Clin. Immunol. 81: 266 (Ab) (1988)), and immunoelectrophoresis (Matthiesen et al., supra, 1988).
The major allergen of Bermuda grass pollen allergen has been identified as a protein with a molecular weight (MW) in the range of 30-34 kD, binding IgE from sera of more than 76% of individuals allergic to Bermuda grass (Ford and Baldo, (1987) Supra; Shen et al, (1988) Supra, and has been designated Cyn dI (Kahn and Marsh, (1986) Mol. Immunol., 23:1281-1288; Marsh et al., (1988) Ann. Allergy, 60:499-504, Matthiesen et al, 1988, Supra). Cyn dI is a member of the Group I family of allergens (Kahn and Marsh, (1986) Supra, found in many taxonomically related grasses including ryegrass (Lol pI), Kentucky bluegrass (Poa pI) and Timothy grass (Phl pI) (Standring et al, 1987 Int. Archs Allergy Appl. Immun., 83, 96-103; Esch and Klapper, (1987) J. Allergy Clin. Immunol., 79:489-495; Matthiesen and Lowenstein (1991) Clin. Exp. Allergy,21, 309-320. However, the allergens of Bermuda grass show limited antibody cross-reactivity with those of other grasses (March et al., Supra, Berstein et al. (1976) J. Allergy Clin. Immunol.,57:141-152. A number of studies have shown that Cyn dI differs from the Group I homologues of closely related grasses (Matthiesen and Lowenstein, (1991) Supra. The sequence of the first 27 amino acids at the N-terminus of Cyn dI has been determined. (Matthiesen et al, 1988, Supra; Matthiesen et al, (1990) Epitopes of Atopic Allergens, Brussels, UCB Institute of Allergy, 9-13; Singh et al, Monographs in Allergy, (1990), 28:101-120; Matthiesen and Lowenstein, (1991), supra).
The presence of Bermuda grass pollen allergens in the environment causes hayfever and seasonal asthma in many individuals and continues to have significant socio-economic impact on Western communities. While the available spectrum of drugs, including anti-histamines and steroids, have resulted in improvement in the treatment of allergic disease, they do have unfortunate side-effects associated with long term usage. Because of these problems, renewed interest has been shown in the immunotherapy of allergic disease. Immunotherapy involves the injection of potent allergen extracts to desensitize patients against allergic reactions (Bousquet, J. and Michel, F. B., (1989) Allergy and Clin Immol. News 1: 7-10. Unfortunately, the pollen preparations used as allergens are polyvalent and of poor quality. Consequently, crude extracts are frequently used at high concentrations and may trigger potentially lethal systemic reactions, including anaphylaxis. The product expressed from the cloned gene, fragments thereof, or synthetic peptides based on the sequence of the allergens provide a safer medium for therapy since they can be quality controlled, characterized and standardized, and they optimally do not bind IgE.
The present invention provides nucleic acid sequences coding for the major protein allergen of the species Cynodon dacrylon (Cyn dI), or at least one fragment thereof or the functional equivalent of such nucleic acid sequences. The present invention also provides expression vectors comprising such nucleic acid sequences and host cells transformed therewith. The present invention further provides isolated recombinantly, chemically or synthetically produced Cyn dI or fragments thereof. Isolated Cyn dI or antigenic fragments thereof are useful for diagnosing and treating sensitivity in an individual to Bermuda grass pollen allergens.